segmentation

slice.py

import math
def to_buckets(lst, *buckets):
    sums = []
    for i in buckets:
        sums.append(sum(lst[:i]))
        lst = lst[i:]
    return sums

def std_dev(target, *values):
    return math.sqrt(sum([(target-i)**2 for i in values]))

def recursive(freq, buckets, optimal, result, level, min_stdev, min_buckets):
    # print(result, level)
    # We don't iterate the last bucket, putting the rest of items
    if(level>=buckets):
        new_buckets = [*result, len(freq) - sum(result)]
        #print(new_buckets)
        b = to_buckets(freq, *new_buckets)
        sd = std_dev(optimal, *b)
        return (sd, new_buckets)    
    else:
        s = sum(result)
        for i in range(1,len(freq)+1):
            if s + i < cnt:
                (min_stdev2, min_buckets2) = recursive(freq, buckets, optimal, result+[i],level+1, min_stdev, min_buckets)
                if min_stdev2 < min_stdev:
                    min_stdev = min_stdev2
                    min_buckets = min_buckets2
                    print(min_stdev, min_buckets)
    return (min_stdev, min_buckets)

def segment(arr, cnt):
    return recursive(arr, cnt, sum(arr)/cnt, [],1, 1, [])

freq = [
    0.0239,
    0.044,
    0.0953,
    0.0183,
    0.0551,
    0.0096,
    0.0024,
    0.0283,
    0.0766,
    0,
    0.0043,
    0.0061,
    0.0293,
    0.0692,
    0.0963,
    0.1539,
    0.0444,
    0.0905,
    0.0313,
    0.0332,
    0.0093,
    0.0042,
    0.0039,
    0.0146,
    0.0036,
    0.0002,
    0,
    0,
    0,
    0.0094,
    0.001,
    0.0019
]
print(segment(freq, 8))